1. Field of the Invention
The present invention relates to a display apparatus for displaying text or images based on text code information constituted of text codes or video signals, particularly to a client display apparatus operating under an external host apparatus.
2. Description of the Related Art
A display apparatus is normally used for displaying text based on text code information or for displaying an image based on a video signal. A conventional display apparatus generally also includes functions of major image processing by which the various processings required for displaying text or images according to text code information/video signal are performed.
Further, display apparatuses are often mounted to other kind of apparatuses. For example, Document 1 (Japanese Unexamined Patent Publication Jitsukaisho 62-201850/1987 (published on Dec. 23, 1987)) discloses a document processing device which displays text information supplied from a keyboard in a display section, and also outputs the text information as voice message by converting the text information into sound information. Further, Document 2 (Japanese Unexamined Patent Publication Tokukaihei 02-165324/1990 (published on Jun. 26, 1990)) discloses a document reader device which interprets document data and displays the data in a display section as an image and also outputs the same data as voice information. Further, Document 3 (Japanese Unexamined Patent Publication Tokukaihei 04-24885/1992 (published on Jan. 28, 1992)) discloses a reading processor device which takes out a text portion from an image and converts the text portion into a text code, which code is then converted into voice information by a voice synthesizer section, so as to output the text information as voice information.
The apparatuses disclosed in Documents 1 through 3 are all capable of outputting voice with their built-in image processing functions which carry out a process for converting text information into voice information.
Meanwhile, a small, light-weighted and thin display apparatus has been available in the market recently, which often serves as a mobile apparatus with a function of capturing an image from an external apparatus. Further, there is a demand for downsizing such a mobile apparatus into a card-size apparatus almost as small as a general credit card, name card etc. Prior to the present invention, the applicant of the present invention suggested in Document 4 (Japanese Unexamined Patent Publication Tokukai 2003-244784 (published on Aug. 29, 2003)) a card-sized display apparatus with voice output function. The apparatus produces sound by vibration of substrate constituting the display element, based on a voice signal supplied from an external apparatus. The display apparatus thus realizes a speaker function without increasing the apparatus size.
With the recent development of network infrastructure or various services, a recent demand for a display apparatus is not only mobility but also a wider range of application and a wider communication area, which can be achieved by relying on an external host device (server) for the most functions of the system. In this case the display apparatus is called a client or a thin client, and simply serves as a displaying device. With this arrangement, the display apparatus does not necessarily have to have a built-in function for general image processing.
The described invention of the same applicant for realizing a card-sized display apparatus with voice output function was made in view of this objective. Such a structure contributes to create a display apparatus with great mobility.
Then, the next object to be achieved is provision of various functions to such a display apparatus serving as a client device. The present invention is made in view of this object.